Alanine aminotransferase (ALT/GPT) catalyzes the transfer of the amino group from alanine to alpha-ketoglutarate, forming glutamate and pyruvate. The latter is reduced to lactate by lactate dehydrogenase (LDH) in the presence of reduced nicotinamide adenine dinucleotide (NADH). The reaction is kinetically monitored at 340 nm by the decrease in absorbance resulting from the oxidation of NADH to NAD+, proportional to ALT activity in the sample.
